Centrifugal drum



May 16, 1967 K. PAUSE 3,319,880

CENTR IFUGAL DRUM Filed April 27, 1965 2 Sheets-Sheet 1 F/G. I a

: I' n I I. II I "1|" I .1 mil Jl J I: 6

I 2 I i 1 1 6 r I I 1 f If INVENI'OR Mu. r 7 Pauxfi Mzad May 16, 1 967 K. PAUSE 3,319,330

CENTRIFUGAL DRUM Filed April 27, 1965 2 Sheets-Sheet 2 United States Patent 3,319,880 CENTRIFUGAL DRUM Kurt Pause, Ledernstrasse 13, Grevenbroich, Germany Filed Apr. 27, 1965, Ser. No. 451,127 Claims priority, application Germany, May 2, 1964,

11 Claims. for. 233 1 Centrifugal drums are known which have a continuous, non-perforated cylindrical casing and end walls in the form of annular discs rigidly connected by welding and preferably also by a shrink fit to opposite ends of the casing. Such centrifugal drums have the advantage that the cylindrical casing can be constructed with a small wall thickness over the main portion of the length thereof, however, during operation of the centrifugal drum and rotation thereof at high speed about its axis there will occur in the planes of the opposite end walls increased bending stresses which will make it necessary to reinforce the end portions of the cylindrical casing of the drum. Therefore, if the drum is to be made with a minimum wall thickness, it is necessary in this case to reduce the wall thickness of the cylindrical casing intermediate its ends, for instance by turning the casing in a lathe, which will obviously considerably increase the manufacturing costs thereof. Furthermore, if the end walls are connected by welding and shrink fitting to the cylindrical casing, the shrinkage stress created in the end portions of the cylindrical casing during shrink fitting thereof onto the end walls is substantially cancelled during the welding operation and resulting heating of the welded portions to a high temperature, so that the bending stresses at the annular portions of the cylindrical casing to which the end walls are connected will vary between zero and a maximum value during operation of the centrifugal drum.

It is an object of the present invention to overcome these disadvantages of centrifugal drums according to the prior art.

It is an additional object of the present invention to provide for a centrifugal drum having a non-perforated cylindrical casing of substantially uniform wall thickness and end wall means connected to the opposite ends of the casing in such a manner that the maximum bending stresses occurring at the connection during operation of the drum are considerably reduced.

It is a further object of the present invention to provide for a method of manufacturing centrifugal drums of the aforementioned type assuring reduced bending stresses at the region of the opposite ends of the cylindrical casing to which the end wall means are connected.

With these objects in view, the centrifugal drum according to the present invention mainly comprises a centrifugal casing having opposite open ends, a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed flange portion extending substantially in direction of the axis of the drum and engaging with the outer surface thereof the inner surface of the casing and being formed with a plurality of axial extending angularly spaced slots therethrough.

With this arrangement the shrinkage stresses created during shrink fitting 0f the end wall means in the opposite ends of the cylindrical casing will be fully maintained in the respective planes of the transverse wall portions of the end wall means, while the slotted flange portions will oppose the bending deformation occurring in the cylindrical casing during operation of the drum only to a minor extent. Due to the aforementioned connection of the end wall means to the cylindrical casing will the shrinkage stresses at the opposite end portions of the casing and the deformation of the end portions resulting from the shrink fitting thereof onto the end wall means be maintained, which in turn will counteract the bending deformation occurring in the cylindrical casing during the maximum rotation speed of the drum in the connection of end Wall means end casing. Due to the predeformation of the opposite ends of the cylindrical casing during the shrink fitting of the end wall means thereinto will the bending stresses occurring in the casing during operation of the drum be greatly reduced.

In order to reduce the bending deformation at the connection of the end wall means and easing, it is also pre ferred to form the outer surface of the annular flange portion of the end wall means as a frustoconical surface having a small cone angle and its smallest diameter at the end edge of the annular flange portion.

In order to further secure the end wall means to the cylindrical casing, it is preferred to fasten the flange portions by screws to corresponding portions of the casing or to spot weld the flange portions to the casing preferably in the region of corresponding end faces of flange portions and casing.

The drum construction according to the present invention permits also to provide the necessary openings for discharging the centrifuged liquid without weakening the casing by forming in a peripheral portion of the transverse wall portions of the end wall means slots respectively aligned with the corresponding slots in the flange portions of the end wall means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is an axial cross section through centrifugal drum according to the present invention;

FIG. 2 is a top view of the drum shown in FIG. 1;

FIG. 3 is a cross section along the line IIIIII of FIG. 2 and drawn to an enlarged scale; and

FIG. 4 is a cross section along the line IVIV of FIG. 2 and likewise drawn to an enlarged scale.

Referring now to the drawings, and more particularly to FIGS. 1 and 2 of the same, it will be seen that the centrifugal drum according to the present invention comprises a cylindrical, non-perforated casing 4 of substantially uniform wall thickness and a pair of end wall means tightly fitted in opposite ends of the cylindrical casing and each having a transverse annular and disc-shaped wall portion respectively designated 1 and 2 located inwardly of the respective end of the casing 4 and an outwardly directed annular flange portion 3 extending substantially in direction of the axis of the drum and engaging with the outer surface thereof the inner surface of the casing. Each of the annular flange portions 3 is formed with a plurality of slots 5 which are equally spaced from each other and which extend in axial direction from the free edge of the flange portion 3 up to the respective transverse wall portion. The free edge faces of the flange portions 3 are substantially flush with the opposite edge faces of the cylindrical casing 4. The outer surface of each flange portion 3 is preferably formed as frustoconical surfaces having a small cone angle. The small diameter of the frustoconical surface is located at the outer free edge of the flange portion 3.

The transverse portions 1 and 2 of the end wall means are manufactured with an outer diameter greater than the inner diameter of the casing 4 at the opposite ends I thereof, and the end wall means are fastened in the oppo- 3 site ends of the casing 4 by shrink fitting. The difference between the outer diameter of the transverse portions 1 and 2 of the end wall means and the inner diameter of the casing 4 at the opposite ends thereof before shrink fitting is preferably chosen in such a manner that after shrink fitting of the casing 4 onto the end wall means, the casing 4 will be expanded in the planes of the transverse portions 1 and 2 of the end wall means to half of the maximum expansion occurring at a central portion of the casing during operation of the centrifugal drum.

FIG. 3 illustrates the centrifugal drum not stressed by centrifugal forces. Due to the shrink fitting of the end portions of the casing 4 onto the transverse wall portions 1 and 2 of the end wall means, the end portions of the durm 4 have been expanded and this expansion is greatest, as shown in FIG. 3 in the plane of the transverse wall portions 1 and 2 of the end wall means and due to the conical configuration of the flange portion 3 of the end wall means, smallest at the outer free edge of the casing 4. Since the annular flange portions of the end wall means 1 and 2 are separated by the slots 5 in a plurality of adjacent fingers, these fingers will, during cooling of the end portions of the casing 4, also be bent slightly inwardly as best shown in FIG. 4.

During operation of the centrifugal drum and rotation thereof at high speed about its axis, the cylindrical casing will be subjected, as known, to an outward expansion as illustrated in FIG. 4 and, as mentioned before, the outer diameter of the wall portions 1 and 2 and the inner diameter of the casing 4 before assembly is chosen in such a way so that the maximum outward expansionoccurring in the casing 4 during operation of the drum is substantially twice the outward deformation which occurs in the end portions of the casing in the planes of the transverse wall portions 1 and 2 after shrink fitting the end portions of the casing onto the end wall means.

In order to transmit the axial forces acting on the end wall means during operation of the centrifugal drum onto the cylindrical casing, the flange portions 3 of the end wall means are secured to the end portions of the cylindrical casing 4 by screws 10, one of which is shown in FIG. 4. Instead of securing the annular flange portions 3 and the casing 4 by screws to each other, it is also possible to spot weld the flange portions 3 to the end portions of the casing 4 and such spot welding is preferably made at or adjacent to edge faces of casing and flange portions 3 as indicated at 11 in FIG. 3.

In order to avoid weakening of the cylindrical casing by the necessary openings for the outflow of the centrifuged liquid from the drum, it is preferred to form in the outer peripheral region of the transverse wall portions 1 and 2 of the end wall means a plurality of slots 6 extending in axial directions through the transverse wall portions and in radial direction a short distance from the outer periphery thereof, and the slots 6 are respectively aligned with the slots 5 in the annular Wall portions 3.

The drum includes also, as schematically indicated in FIGS. 3 and 4, inner sieve means 8 arranged about the inner surface of the casing 4 and inwardly of the inner ends of the slots 6 and supported on the inner surface of the casing 4 by spacer sieve means 7 so that the liquid to be centrifuged may pass through the inner sieve means 8 and along the supporting sieve means 7 through the slots 6 in the transverse wall portions 1 and 2 and through the slots 6 in the flange portions to the outside of the drum.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of centrifugal drums differing from the types described above.

While the invention has been illustrated and described as embodied in centrifugal drums having a pair of end wall means shrink fitted in opposite ends of a cylindrical casing, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends; and a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion extending substantially in direction of the axis of said drum and engaging with the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough.

2. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends; and a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion extending substantially in direction of the axis of said drum and engaging with the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough, each of said flange portions having an outer edge face substantially flush with a corresponding edge face of said cylindrical facing.

3. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends and a pair of frustoconical end portions of small cone angle each having its smallest diameter at the respective open end of said casing; and a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion tapering substantially at the same angle as the respective frustoconical end portions of said casing so as to engage with the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough, each of said flange portions having an outer edge face substantially flush with a corresponding edge face of said cylindrical facing.

4. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends; a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion extending substantially in direction of the axis of said drum and engaging with the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough; and means securing said flange portions to said cylindrical casing.

5. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends and a pair of frustoconical end portions of small cone angle each having its smallest diameter at the respective open end of said casing; a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion tapering substantially at the same angle as the respective frustoconical end portions of said casing so as to engage With the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough; and screw means connecting said flange portions to said casing.

6. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends and a pair of frustoconical end portions of small cone angle each having its smallest diameter at the respective open end of said casing; a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion tapering substantially at the same angle as the respective frustoconical end portions of said casing so as to engage with the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough; and weld means connecting said flange portions to said casing.

7. In a centrifugal drum, in combination, a continuous cylindrical casing having opposite open ends; and a pair of end wall means shrink fitted in said open ends and each having a transverse wall portion extending transversely through and inwardly of the respective open end and an outwardly directed annular flange portion extending substantially in direction of the axis of said drum and engaging with the outer surface thereof the inner surface of said casing, said annular flange portion being formed with a plurality of axially extending angularly spaced slots therethrough, each of said transverse wall portions being formed at the outer periphery thereof with a plurality of short slots therethrough respectively axially aligned with slots in said flange portion.

8. A centrifugal drum comprising, in combination, a cylindrical casing having a continuous wall of uniform thickness, a pair of open ends and a pair of frustoconical end portions of small cone angle and each having its smallest diameter at the respective open end of said casing; a pair of end wall means shrink fitted in said open ends of said casing and each having a transverse wall portion extending transversely and inwardly of the re spective open end and an outwardly directed flange portion tapering substantially at the same angle as the respective frustoconical end portion of said casing so as to engage with the outer surface thereof the inner surface of the respective end portion, each of said flange portions having an outer edge face substantially flush with a corresponding edge face of said casing and being formed with a plurality of substantially equally spaced axially extending slots therethrough and said transverse wall portion being formed in an outer peripheral region thereof with a plurality of shallow slots therethrough respectively aligned with corresponding slots through said flange portion; means securing said flange portions to the corresponding end portions of said casing; and sieve means about the inner surface of said casing and including an inner sieve located radially inwardly of said slots through said transverse wall portions and a supporting sieve sandwiched between the inner surface of said casing and the outer surface of said inner sieve to support the latter in said casing inwardly spaced from the inner surface thereof so that liquid to be centrifuged may pass from the interior of said sieve means through the latter and through said slots in said transverse wall portions and said flange portions to the outside of said drum.

9. A method of manufacturing a centrifugal drum comprising the steps of forming a cylindrical casing having opposite open ends of a given inner diameter; forming a pair of end wall means having each a transverse wall portion of a diameter slightly greater than said given diameter and being formed in an outer peripheral portion thereof with a plurality of axially extending shallow slots therethrough circumferentially spaced from each other, and an annular flange portion extending substantially normal to and from said outer peripheral portion of said transverse wall portion and being formed with a plurality of axially extending slots therethrough respectively axially aligned with said slots in said transverse wall portion; shrink-fitting said pair of end wall means into said open ends of said casing with said transverse wall portions located inwardly of said open ends and said flange portions respectively extending in outward direction and engaging corresponding portions of said casing; and securing said flange portions to said portions of said casing.

10. A method as set forth in claim 9 and including the step of forming the outer surfaces of each flange portion as frustoconical surface having a small cone angle and the small diameter of the frustoconical surface at the edge face of the flange portion.

11. A method of manufacturing a centrifugal drum comprising the steps of forming a cylindrical casing having opposite open ends of a given inner diameter; forming a pair of end wall means having each a transverse wall portion of a diameter slightly greater than said given diameter and being formed in an outer peripheral portion thereof with a plurality of axially extending shallow slots therethrough circumferentially spaced from each other, and an annular flange portion extending substantially normal to and from said outer peripheral portion of said transverse wall portion and being formed with a plurality of axially extending slots therethrough respectively axially aligned with said slots in said transverse wall portion; shrink-fitting said pair of end wall means into said open ends of said casing with said transverse wall portions located inwardly of said open ends and said flange portions respectively extending in outward direction and engaging corresponding portions of said casing; and securing said flange portions in the region of the edge faces thereof by spot Welding to said casing.

References Cited by the Examiner UNITED STATES PATENTS 2,401,231 5/1946 Crawford 29447 X 2,657,803 11/1953 Schutte 2332 2,683,562 7/1954 Ranseen 2332 X 2,872,105 2/1959 Rushing 23327 3,212,843 10/1965 Boyland 233-27 3,282,498 11/1966 Smith 233-27 M. CARY NELSON, Primary Examiner. 

1. IN A CENTRIFUGAL DRUM, IN COMBINATION, A CONTINUOUS CYLINDRICAL CASING HAVING OPPOSITE OPEN ENDS; AND A PAIR OF END WALL MEANS SHRINK FITTED IN SAID OPEN ENDS AND EACH HAVING A TRANSVERSE WALL PORTION EXTENDING TRANSVERSELY THROUGH AND INWARDLY OF THE RESPECTIVE OPEN END AND AN OUTWARDLY DIRECTED ANNULAR FLANGE PORTION EXTENDING SUBSTANTIALLY IN DIRECTION OF THE AXIS OF SAID DRUM AND ENGAGING WITH THE OUTER SURFACE THEREOF THE INNER SURFACE OF SAID CASING, SAID ANNULAR FLANGE PORTION BEING FORMED WITH A PLURALITY OF AXIALLY EXTENDING ANGULARLY SPACED SLOTS THERETHROUGH. 